Electronic device using solar cell

ABSTRACT

An electronic device comprises a solar cell a main body which includes a display unit, a battery, and a processing unit and a power controller which connects the solar cell and the main body and controls the electronic device so that power generated from the solar cell is stored in the battery or used in the main body depending on a state of the main body.

This application claims priority to Korean Patent Application No.10-2011-0031754, filed on Apr. 6, 2011, the content of which in itsentirety is herein incorporated by reference.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The general inventive concept relates to an electronic device using asolar cell, and more particularly, to an electronic device capable ofcontrolling an output of the solar cell according to an operationalstate of the electronic device.

(b) Description of the Related Art

A solar cell converting photonic energy, e.g., solar energy, intoelectric energy has been recognized as renewable and non-pollutingnext-generation energy.

The solar cell typically includes a p-type semiconductor and an n-typesemiconductor. In the solar cell, when photonic energy, e.g., sun lightenergy, is absorbed in an optical active layer, an electron-hole pair(“EHP”) is generated in a semiconductor and electrons and holesgenerated due to the photonic energy move to the n-type semiconductorand the p-type semiconductor, respectively and are collected inelectrodes so as to be used as the electric energy.

However, since it is substantially difficult to arbitrarily control theintensity of sun light which an output (voltage or current) of the solarcell depends on, it is substantially difficult to utilize the solarcell.

BRIEF SUMMARY OF THE INVENTION

The general inventive concept provides an electronic device having anadvantage of actively utilizing an output of a solar cell according toan operational state of the electronic device.

An exemplary embodiment of the invention provides an electronic deviceincluding a solar cell, a main body which includes a display unit, abattery, and a processing unit, and a power controller which connectsthe solar cell and the main body and controls the electronic device sothat power generated from the solar cell is stored in the battery orused in the main body depending on a state of the main body.

In one exemplary embodiment, the power controller may include an inputterminal for the solar cell which receives an output of the solar cell,an output terminal for storage connected with an input terminal of thebattery of the main body, an output terminal for consumption connectedwith a power terminal of the display unit or the processing unit of themain body, and an input terminal for the battery connected with anoutput terminal of the battery which supplies the power to the powerterminal of the display unit or the processing unit of the main body.

In one exemplary embodiment, the power controller may transmit theoutput of the solar cell inputted to the input terminal for the solarcell to the battery through the output terminal for the storage, whenthe display unit or the processing unit of the main body does notoperate.

In one exemplary embodiment, the power controller may transmit theoutput of the solar cell inputted to the input terminal for the solarcell to the display unit or the processing unit of the main body throughthe output terminal for consumption, when the display unit or theprocessing unit of the main body operates.

In one exemplary embodiment, the power controller may combine an outputof the battery inputted from the input terminal for the battery and theoutput of the solar cell to output the combined output to the outputterminal for consumption.

In one exemplary embodiment, the power controller may store a part ofthe output of the solar cell inputted to the input terminal of the solarcell in the battery through the output terminal of the storage.

In one exemplary embodiment, the power controller may further include aswitching unit which is connected between the input terminal for thesolar cell and the output terminal for the storage and operatesdepending on an input value of the input terminal for the battery, and apower output unit which is connected with the input terminal for thesolar cell and the input terminal for the battery to receive the outputof the solar cell and the output of the battery and combines the outputof the solar cell and the output of the battery to transmit the combinedoutput to the output terminal for consumption.

In one exemplary embodiment, the power output unit may include an inputdiode for the solar cell connected in a forward direction from the inputterminal for the solar cell, and an input diode for the batteryconnected in a forward direction from the input terminal for thebattery.

In one exemplary embodiment, the switching unit may include a switchingunit transistor, and an input terminal of the switching unit transistormay be connected to the input terminal for the solar cell, an outputterminal of the switching unit transistor may be connected to the outputterminal for the storage, and a control terminal may be connected withthe input terminal for the battery.

In one exemplary embodiment, the power controller may further include adiode which prevents power leak of the battery connected between theoutput terminal of the switching unit transistor and the output terminalfor the storage in a forward direction from the output terminal of theswitching unit transistor.

In one exemplary embodiment, the power controller may further include aswitch controller formed between the input terminal for the battery andthe control terminal of the switching unit transistor, the switchcontroller may include a switch controller transistor, and an inputterminal of the switch controller transistor may be connected with thecontrol terminal of the switching unit transistor, an output terminalmay be connected with a ground, and a control terminal may be connectedwith the input terminal for the battery.

In one exemplary embodiment, a first resistor may be formed between theoutput terminal of the switch controller transistor and ground, a firstnode may be disposed between the control terminal of the switchcontroller transistor and the input terminal for the battery, the firstnode may be connected with the ground through a second resistor, and thesecond resistor may have a resistance higher than that of the firstresistor.

In one exemplary embodiment, the first node may be also connected withthe power output unit and an input diode for the battery formed in aforward direction from the first node may be included in the poweroutput unit.

In one exemplary embodiment, the switching unit transistor and theswitch controller transistor may be PNP type transistors.

In one exemplary embodiment, the electronic device may further includean input terminal capacitor connected between the input terminal for thesolar cell and the ground.

In one exemplary embodiment, the processing unit may include an inputdevice.

According to exemplary embodiments of the disclosure, an electronicdevice can actively control an output of a solar cell to be stored in abattery or consumed in accordance with an operational state thereof.

As a result, the output of the solar cell can be efficiently used and inthe case of a portable electronic device, the electronic device can beused at the same time as a battery is charged through the solar cell.

Further, since a power controller for controlling the solar cell canalso be formed by several analog elements, a manufacturing cost is notsignificantly increased.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other advantages and features of this disclosure willbecome more apparent by describing in further detail embodiments thereofwith reference to the accompanying drawings, in which:

FIG. 1 is a block diagram of an exemplary embodiment of an electronicdevice using a solar cell.

FIG. 2 is a detailed block diagram of an exemplary embodiment of adisplay device.

FIG. 3 is a circuit diagram of an exemplary embodiment of a powercontroller.

FIG. 4 is an operational flowchart of an exemplary embodiment of a powercontroller.

FIGS. 5 to 7 are graphs measuring and simulating voltage of an exemplaryembodiment of a switching unit transistor of a power controlleraccording to brightness of a display device.

FIGS. 8 and 9 are graphs measuring and simulating voltage with an inputterminal capacitor of a power controller added according to an exemplaryembodiment of the invention.

FIGS. 10A to 10C are graphs illustrating an exemplary embodiment of anoperation of an electronic device depending on the type of a solar cell.

FIG. 11 is a diagram showing an exemplary embodiment of an operation ofan electronic device depending on use modes for various solar cells.

FIG. 12 is a graph showing voltage and current characteristics dependingon a type of a solar cell.

DETAILED DESCRIPTION OF THE INVENTION

The invention will be described more fully hereinafter with reference tothe accompanying drawings, in which exemplary embodiments of theinvention are shown. As those skilled in the art would realize, thedescribed embodiments may be modified in various different ways, allwithout departing from the spirit or scope of the invention.

In the drawings, the thickness of layers, films, panels, regions, etc.,are exaggerated for clarity. Like reference numerals designate likeelements throughout the specification. It will be understood that whenan element such as a layer, film, region, or substrate is referred to asbeing “on” another element, it can be directly on the other element orintervening elements may also be present. In contrast, when an elementis referred to as being “directly on” another element, there are nointervening elements present.

It will be understood that, although the terms first, second, third,etc., may be used herein to describe various elements, components,regions, layers and/or sections, these elements, components, regions,layers and/or sections should not be limited by these terms. These termsare only used to distinguish one element, component, region, layer orsection from another region, layer or section. Thus, a first element,component, region, layer or section discussed below could be termed asecond element, component, region, layer or section without departingfrom the teachings of the invention.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a,” “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the relevant art andwill not be interpreted in an idealized or overly formal sense unlessexpressly so defined herein.

All methods described herein can be performed in a suitable order unlessotherwise indicated herein or otherwise clearly contradicted by context.The use of any and all examples, or exemplary language (e.g., “suchas”), is intended merely to better illustrate the invention and does notpose a limitation on the scope of the invention unless otherwiseclaimed. No language in the specification should be construed asindicating any non-claimed element as essential to the practice of theinvention as used herein.

Hereinafter, the invention will be described in detail with reference tothe accompanying drawings.

Exemplary embodiments of the invention provide actively controlling anoutput of a solar cell 200 according to an operational state of anelectronic device 100, According to the exemplary embodiments, theoutput of the solar cell 200 is stored in a battery 430 while theelectronic device 100 is not used, and the output of the solar cell 200is controlled to be substantially immediately used for the electronicdevice 100 while the electronic device 100 is used.

In one exemplary embodiment, when the electronic device 100 uses lowerpower (voltage or current) than the output of the solar cell 200,remaining power may be stored in a battery 430.

Exemplary embodiments of the disclosure may be applied to various typesof electronic devices, but it may be substantially effective to beapplied to a portable electronic device.

The portable electronic devices may include a mobile phone, a smartphone, a laptop computer, a netbook, a tablet personal computer (“PC”),a portable multimedia player (“PMP”), an MPEG-1 Audio Layer 3 (“MP3”)player, a compact disk (“CD”) player, a portable game device, anavigation device, for example, but are not limited thereto.

Furthermore, typically, a display unit is a part which consumes arelatively large amount of power compared other parts in the portableelectronic device is a display unit. The display unit may include aliquid crystal display (“LCD”) unit, an electrophoretic display unit, anorganic light emitting display (“OLED”) unit, for example, but is notlimited thereto.

Hereinafter, an exemplary embodiment of a laptop computer which consumesa relatively large amount of power among portable electronic deviceswill be described. The exemplary embodiment of the laptop computer mayuse a liquid crystal display unit as a display unit. However, thegeneral inventive concept is not limited thereto, and other varioustypes of an electronic device including other various types of a displayunit may be used.

Hereinafter, an exemplary embodiment of an electronic device and anoperational order thereof will be described with reference to FIGS. 1 to4.

FIG. 1 is a block diagram of an exemplary embodiment of an electronicdevice using a solar cell, FIG. 2 is a detailed block diagram of anexemplary embodiment of a display device, FIG. 3 is a circuit diagram ofan exemplary embodiment of a power controller, and FIG. 4 is anoperational flowchart of an exemplary embodiment of a power controller.

First, referring to FIG. 1, a connection relation of an exemplaryembodiment of the electronic device 100 is shown by a block diagram.

The exemplary embodiment of the electronic device 100 (e.g., laptopcomputer) includes a solar cell 200, a power controller 300, and a mainbody 400.

First, the main body 400 includes a display unit 410, a processing unit420, and a battery 430 and the processing unit 420 includes an inputdevice 421. The display unit 410 and the processing unit 420 of the mainbody 400 are connected to each other through a cable. In the exemplaryembodiment, the display unit 410 receives an output of the powercontroller 300 to transfer the output to the processing unit 420.Furthermore, in the exemplary embodiment, an output terminal 431 and aninput terminal 432 of the exemplary embodiment of the battery 430 areconnected to the power controller 300 via the processing unit 420 andthe display unit 410. The display unit 410 and the processing unit 420receive the power from the power controller 300 through power terminalswhich are formed in the display unit 410 and the processing unit 420,respectively. In the exemplary embodiment, the input device 421 includesvarious types of electronic devices such as a laptop computer, acellular phone, a keyboard, a mouse, or a touch screen, for example, butis not limited thereto.

FIG. 2 is a block diagram schematically showing a backlight unit 411used in a case where the display unit 410 of the main body 400 is alight-receiving type display unit such as the LCD unit, for example, andthe backlight unit 411 includes a controller 411-1 and a light source411-2. The controller 411-1 receives the power from a P2 terminal of thepower controller 300, and then, transfers the power to the light source411-2. In addition, luminance of the light source 411-2 is controlled bycontrolling a pulse width modulation PWM (or feedback FB) signal fromthe controller 411-1. Herein, the luminance control of the light source411-2 may be controlled on a basis of a duty ratio of the PWM (or FB)signal.

In the exemplary embodiment, the solar cell 200 is connected to a P1input terminal of the power controller 300. The solar cell 200 may beelectrically connected with the power controller 300 through twoindividual terminals of the P1 input terminal, i.e., a positive (+)terminal and a negative (−) terminal. An output (e.g., power voltage orcurrent) of the solar cell 200 may be transferred through the positive(+) terminal, and the negative (−) terminal may be connected to thepower controller 300 through a ground terminal of the power controller300.

The power controller 300 has two input terminals P1 and P4 and twooutput terminals P2 and P3.

The P1 input terminal is connected with the solar cell 200 and may bealso referred to as an input terminal for the solar cell.

The P2 output terminal is an output terminal connected with the mainbody 400 to output the power so that the display unit 410 including thebacklight unit 411 or the processing unit 420 including the input device421 of the main body 400 can use the power. The P2 output terminal maybe also referred to as an output terminal for consumption. The P2 outputterminal is connected with the power terminal of the display unit 410 orthe processing unit 420 in the main body 400 through a connectorconnecting the main body 400 and the power controller 300 to supply thepower. Referring to FIG. 2, the connection of the backlight unit 411 ofthe display unit 410 and the P2 output terminal is shown.

In an electronic device, typically, the power is directly supplied tothe display unit 410 or the processing unit 420 from the battery 430 inthe main body 400, but in the exemplary embodiment of electronic device100, the output of the battery 430 is transferred to the display unit410 or the processing unit 420 via the power controller 300.

In one exemplary embodiment, the P4 input terminal is connected with theoutput terminal 431 of the battery 430 and may be also referred to as aninput terminal for a battery. In the above described exemplaryembodiment, the output terminal 431 of the battery 430 is electricallyconnected to the P4 input terminal via the connector connecting the mainbody 400 and the power controller 300.

In the exemplary embodiment, the P3 output terminal is connected withthe input terminal 432 of the battery 430, transfers the power of thesolar cell 200 to the battery 430. The P3 output terminal may be alsoreferred to as an output terminal for storage. The P3 output terminal iselectrically connected with the input terminal 432 of the battery 430via the connector connecting the main body 400 and the power controller300.

The power controller 300 transmits the output of the solar cell 200inputted into the P1 input terminal to the P3 output terminal to bestored in the battery 430 or transmits the output to the P2 outputterminal to be consumed in the display unit 410 or the processing unit420 of the main body 400. An operation of a switch in the powercontroller 300 determines whether the power controller 300 transmits theoutput of the solar cell 200 to the P3 output terminal or the P2 outputterminal. The operation of the switch of the power controller 300 willbe described below in detail referring to FIG. 3.

Furthermore, the output of the battery 430 inputted to the P4 inputterminal is also transmitted to the P2 output terminal to be consumed inthe display unit 410 or the processing unit 420 of the main body 400.Therefore, a sum of the inputs of the P1 input terminal and the P4 inputterminal is transmitted to the P2 output terminal, the main body 400operates based on the output of the battery 430 from the P4 inputterminal in a case of a small output of the solar cell 200, and the mainbody 400 operates with only the output of the solar cell 200 from the P1input terminal in a case of a sufficient output of the solar cell 200.In one exemplary embodiment, when the output of the solar cell 200remains after operating the main body 400, the remaining output may bealso stored in the battery 430 through the P3 output terminal. That is,while the power consumption required in the main body 400 is appliedthrough the P2 output terminal, the power inputted from the battery 430becomes substantially smaller when the output of the solar cell 200supplied to the P2 becomes substantially larger, thereby the powerconsumption of the battery 430 substantially decreases.

As described above, the operation of the power controller 300 isschematically shown as a flowchart in FIG. 4.

The power controller 300 determines whether or not the main body 400operates (S10).

When the main body 400 does not operate, the power controller 300transmits the power inputted through the P1 input terminal to thebattery 430 through the P3 output terminal, thereby charging the battery430 (S30).

In the exemplary embodiment, when the main body 400 operates, the powercontroller 300 compares current consumed to the P2 output terminal(i.e., backlight consumption current in FIG. 4) with current inputted tothe P1 output terminal (i.e., solar cell output current in FIG. 4)(S20).

As a result, when the backlight consumption current is larger than thesolar cell output current, a whole current inputted from the solar cell200 is used and a further required current is supplied from the battery430 (S40), and when the backlight consumption current is smaller thanthe solar cell output current, a remaining current of a current inputtedfrom the solar cell 200 is used to charge the battery 430 (S50).

FIG. 3 shows an exemplary embodiment of the power controller 300 but thepower controller 300 operating as described above may be manufactured invarious structures. In one exemplary embodiment, the power controller300 as shown in FIG. 3 may include only a few analog elements, therebyreducing manufacturing costs.

An exemplary embodiment of a detailed circuit structure of the powercontroller 300 will be described with reference to FIG. 3.

The exemplary embodiment of the power controller 300 includes aswitching unit 323, a power output unit 321, and a switch controller322.

The power output unit 321 combines the output of the solar cell 200inputted from the P1 input terminal and the output of the battery 430from the P4 input terminal to transmit the combined output to the mainbody 400. The power output unit 321 includes a D0 diode (also referredto as an input diode for a solar cell) connected from the P1 inputterminal to the P2 output terminal (forward direction) and a D1 diode(also referred to as an input diode for a battery) connected from the P4input terminal to P2 output terminal (forward direction) and has astructure in which outputs of the D0 diode and the D1 diode are combinedto be transmitted to the P2 output terminal.

In the exemplary embodiment, the switching unit 323 includes a switchingunit transistor TR0 and the exemplary embodiment of the switching unittransistor TR0 includes a PNP type transistor. An input terminal of theswitching unit transistor TR0 is connected to the P1 input terminal, anoutput terminal is connected to the P3 output terminal, and a controlterminal is connected with the P4 input terminal through the switchcontroller 322. That is, the switching unit 323 operates the switchingunit transistor TR0 according to a signal of the switch controller 322that operates depending on a signal of the P4 input terminal. When theswitching unit transistor TR0 is in an on state, the power of the solarcell 200 inputted to the P1 input terminal is outputted to the P3 outputterminal to be stored in the battery 430. In the exemplary embodiment,referring to FIG. 3, a D3 diode 324 for preventing the battery powerfrom being leaked is additionally formed between the output terminal ofthe switching unit transistor TR0 and the P3 output terminal. The D3diode is connected toward the P3 output terminal from the switching unit323 in a forward direction to transmit the output of the solar cell 200to the battery 430 and acts to prevent the power from overflowing to theswitching unit 323 from the battery 430 in a reverse direction.

The switch controller 322 controlling the switching unit 323 includes aswitch controller transistor TR1. In the exemplary embodiment, theswitch controller transistor TR1 includes a PNP type transistor. Aninput terminal of the switch controller transistor TR1 is connected withthe control terminal of the switching unit transistor TR0 of theswitching unit 323, an output terminal is grounded through an R1resistor, and a control terminal is connected to the P4 input terminal,an R2 resistor, and an anode of the D1 diode of the power output unit321 through an N node.

The R2 resistor has a resistance significantly larger than that of theR1 resistor and the R1 resistor may be formed with an actual element,such as resistor made of various compounds and films, but is not limitedthereto, and may mean a resistance of a wire.

The N node transmits the power of the battery 430 transmitted from theP4 input terminal to the D1 diode of the power output unit 321. When theP4 input terminal is floated as the main body 400 stops operating, theswitch controller transistor TR1 is turned on. When the power of thebattery 430 is transmitted to the D1 diode of the power output unit 321,the R2 resistor may have a large resistance sufficient not to leak intothe ground terminal.

In the exemplary embodiment, an input terminal capacitor C0 which isconnected with the ground in series is connected parallel to the P1input terminal and acts to stabilize the output from the solar cell 200.In addition, in one exemplary embodiment, an on/off operationcharacteristic of the switching unit transistor TR0 may be changed byadjusting a size of the input terminal capacitor C0 to be controlledsuch that a part of the power supplied from the solar cell 200 is storedinto the battery 430 or the entire power is used in the main body 400.The above described exemplary embodiment will be further described inFIGS. 8 and 9.

An exemplary embodiment of an operation of the power controller 300having the structure described above will be described below.

First, when the main body 400 does not operate, the P4 input terminal isfloated. As a result, a current flows in the control terminal of theswitch controller transistor TR1 by the R2 resistor, such that theswitch controller transistor TR1 is turned on. When the switchcontroller transistor TR1 is turned on, a current flows in the controlterminal of the switch controller transistor TR0 by the R1 resistor,such that the switching unit transistor TR0 is also turned on. As aresult, the output inputted through the P1 input terminal from the solarcell 200 passes through the D3 diode and the P3 output terminal via theswitching unit 323 to be transmitted and charged in the input terminal432 of the battery 430 (Charging mode). In this case, the output of thesolar cell 200 inputted through the P1 input terminal may be transmittedto the D0 diode of the power output unit 321, but since the main body400 does not operate and a load at the P2 output terminal is very large,the output transmitted to the power output unit 321 is substantiallyinsignificant.

In the exemplary embodiment, when the main body 400 operates, outputvoltage of the battery 430 is applied to the P4 input terminal. Theexemplary embodiments of the output voltage of the battery 430 may havea value of about 9 to about 13V, such that the switch controllertransistor TR1 is turned off and accordingly, the switching unittransistor TR0 is also turned off. As a result, the output of the solarcell 200 is not transmitted to the P3 output terminal and the output ofthe solar cell 200 is consumed in the display unit 410 or the processingunit 420 of the main body 400 through the P2 output terminal (Reductionmode).

In the exemplary embodiment, in the exemplary embodiment, the output ofthe solar cell 200 may be charged in the battery and partially consumedin the main body 400 (Charging and Reduction mode).

The Charging and Reduction mode, as the case where all the output of thesolar cell 200 is transmitted to the P2 output terminal and the P3output terminal, may be controlled by various methods and hereinafter,an exemplary embodiment of the backlight unit 411 using a feedback (FB)signal or a pulse width modulation signal PWM will be described.

The backlight unit 411 includes the light source 411-2 and thecontroller 411-1 as shown in FIG. 2, receives the feedback (FB) signalin order to adjust brightness of the light source 411-2 to control aduty ratio of the PWM signal and be applied to the light source 411-2,such that luminance of the backlight unit 411 is controlled. That is,the PWM signal includes a high period and a low period and in the highperiod, the light source 411-2 keeps the state of on and in the lowperiod, the light source 411-2 is turned off. In the above describedexemplary embodiment, the feedback (FB) signal has high/low periodsopposite to the PWM signal. Accordingly, in a period when the lightsource 411-2 is lighted on, the power controller 300 transmits theoutput of the solar cell 200 to the backlight unit 411 through the P2output terminal to light-on the light source 411-2, and in a period whenthe light source 411-2 is lighted off, the power controller 300 canstore the output of the solar cell 200 in the battery 430 through the P3output terminal.

A change of the voltages of the input terminal and the control terminalof the switching unit transistor TR0 depending on the PWM signal (or thefeedback FB signal) will be described with reference to FIGS. 5 to 7.

FIGS. 5 to 7 are graphs measuring and simulating exemplary embodimentsof voltages of a switching unit transistor of a power controlleraccording to brightness of a display device.

First, FIG. 5 shows an exemplary embodiment in which the high period ofthe feedback (FB) signal is substantially long and the low period of thefeedback (FB) signal is substantially short, and a result, an off stateis long, and FIGS. 6 and 7 show exemplary embodiments in which an onstate is extended as time elapsed, and as a result, the backlight unit411 maintains the on state during most of the time in FIG. 7.

In addition, FIGS. 5, 6, and 7 each includes two graphs, an upper graph(measure) is a graph actually measuring voltages in the input terminal(emitter) and the control terminal (base) of the switching unittransistor TR0, and a lower graph (simulation) is a result graphsimulating voltages in the input terminal (emitter) and the controlterminal (base) of the switching unit transistor TR0. However, FIGS. 5,6, and 7 show a result of measurement and simulation while the C0capacitor which is the input terminal capacitor is removed in order toverify voltage variation in the input terminal of the switching unittransistor TR0.

As shown in FIGS. 5 to 7, the voltages of the feedback (FB) signal andthe input terminal and the control terminal of the switching unittransistor TR0 have the substantially same characteristic in a phasechange.

The light source 411-2 of the backlight unit 411 is lighted off in thehigh period of the feedback (FB) signal (the low period of the PWMsignal) and loads of the power controller 300 and the main body 400 aresignificantly large when seen from the solar cell 200.

A characteristic of the solar cell 200 is shown in FIG. 12. When theload of the solar cell 200 is increased (the load is gradually increasedtoward a rightward direction in FIG. 12), the current is decreased, butthe voltage value is increased. As a result, the voltages of the inputterminal and the control terminal of the switching unit transistor TR0connected with the P1 input terminal are also increased.

As a result, a difference between the voltages of the input terminal andthe control terminal of the switching unit transistor TR0 is generatedin the high period of the feedback (FB) signal (the lighted-off periodof the backlight unit) as shown in the lower simulation diagrams ofFIGS. 5 to 7, such that the switching unit transistor TR0 is turned onand the output of the solar cell 200 is charged in the battery 430.

In the exemplary embodiment, the voltages of the input terminal and thecontrol terminal of the switching unit transistor TR0 are the same inthe low period of the feedback (FB) signal (the lighted-on period of thebacklight unit) as shown in the lower simulation diagrams of FIGS. 5 to7, such that the switching unit transistor TR0 is turned off and theoutput of the solar cell 200 is not transmitted to the battery 430.

Even though FIGS. 5 to 7 show the feedback (FB) signal, but even the PWMsignal in which the high period and the low period are reversed mayacquire the same result.

Furthermore, since the feedback (FB) signal in FIGS. 5 to 7 is repeatedin the high and low periods for a substantially short time, inconsidering an operation for a predetermined time, the power controller300 alternately generates the battery charge (Charging mode) and thepower consumption of the main body 400 (Reduction mode) for thepredetermined time, Therefore, the above described exemplary embodimentmay be referred to as the Charging and Reduction mode.

However, in the case where the Charging and Reduction mode is operated,since a charged time in the battery is very short, the battery is notsubstantially charged and charging efficiency may be substantiallydeteriorated. Accordingly, in the case where the main body 400 operates,the output of the solar cell 200 is set to be used in the main body 400as much as possible and in the case where the main body 400 does notoperate, the output is set to be charged in the battery 430, such thatthe efficiency may be substantially improved.

Hereinafter, a graph measuring the voltages of the input terminal andthe control terminal of the switching unit transistor TR0 after addingthe input terminal capacitor C0 will be described with reference toFIGS. 8 and 9.

FIGS. 8 and 9 are graphs measuring and simulating an exemplaryembodiment of voltage with an added input terminal capacitor of a powercontroller.

As shown in FIGS. 8 and 9, a variation range of the output voltage ofthe solar cell 200 inputted through the P1 input terminal issubstantially decreased due to the input terminal capacitor C0.

In the case of the feedback (FB) signal shown in FIGS. 8 and 9, there isno large difference in variation range in the lighted-on period of thebacklight unit 411, and corresponding voltage variations in the inputterminal and the control terminal of the switching unit transistor TR0are shown.

In FIGS. 8 and 9, level 3 and level 4 are described respectively. Thelevels are acquired by dividing the brightness of the backlight unit 411into numerical values of 1 to 10 where a higher numerical valuerepresents higher luminance.

In FIG. 8, in the case of the input terminal and the control terminal ofthe switching unit transistor TR0, according to a lower simulated graph,a difference in voltage between the input terminal and the controlterminal is a maximum difference of about 0.7 V and the minimumdifference of about 0.3 V. Since the switching unit transistor TR0 usedin the exemplary embodiment is turned on when the difference in voltagebetween the input terminal and the control terminal thereof is about 0.7V, the switching unit transistor TR0 maintains the turn-on state for apredetermined time even in the minimum voltage difference, but an outputthrough the output terminal is not substantially large. Therefore, inthe case of the maximum voltage difference, the switching unittransistor TR0 is completely turned on to charge the battery 430, and inthe case of the minimum voltage difference, the power is partiallyconsumed by the backlight unit 411 and the remaining power may becharged in the battery 430, but the power charged in the battery 430 isnot substantially large.

In the exemplary embodiment, referring to FIG. 9, the voltage differencebetween the input terminal and the control terminal of the switchingunit transistor TR0 substantially decreases. According to a lower graphof FIG. 9, the input terminal and the control terminal of the switchingunit transistor TR0 have a maximum voltage difference of about 0.4 V anda minimum voltage difference of about 0 V. Since the voltage differenceof 0.4 V is a level which slightly turn on the switching unit transistorTR0, it may be seen that the switching unit transistor TR0 substantiallymaintains a turn-off state. As a result, the whole output of the solarcell 200 is consumed in the main body 400.

Although a difference in display luminance of the backlight unit 411 isnot substantially large in FIGS. 8 and 9, FIGS. 8 and 9 show thatvoltage values of the input terminal and the control terminal of theswitching unit transistor TR0 vary. Therefore, the power controller 300can operate actively according to the difference in display luminance ofthe backlight unit 411.

Furthermore, the variations of the voltage values of the input terminaland the control terminal of the switching unit transistor TR0 can bechanged by controlling a size of the input terminal capacitor C0, suchthat battery charging (a charging mode) or using the output of the solarcell in the main body (a reduction mode) may be selectively performed bychanging a characteristic of each element of the power controller 300.

In FIGS. 10 and 11, the case of charging the output in the battery andthe case of using the output in the main body are shown through graphsfor easier viewing.

First, an exemplary embodiment shown in FIG. 10 will be described.

FIGS. 10A to 10C are graphs illustrating an exemplary embodiment of anoperation of an electronic depending on a type of a solar cell. In FIGS.10A to 10C, figures on a horizontal axis are arbitrarily divided on thebasis of the brightness of the backlight unit 411. A higher numericalvalue on the horizontal axis represents higher luminance.

FIG. 10A shows that a consumed current substantially increases as theluminance of the backlight unit 411 substantially increases when outputsof two solar cells are 60 mA and 100 mA, respectively.

As a result, according to FIG. 10B, the solar cell generating the outputcurrent of 60 mA charges the battery 430 in brightness levels 1 to 3,but in higher brightness levels (i.e., levels 4 to 10), a whole outputcurrent of the solar cell is consumed in the backlight unit 411 and thebattery supplies a current for an insufficient amount.

In the exemplary embodiment, referring to FIG. 10C, the solar cellgenerating the output current of 100 mA is shown and since the outputcurrent is larger than that of FIG. 10B, the battery is charged togetherunder up to the brightness of level 6.

Hereinafter, FIG. 11 will be described.

FIG. 11 is a diagram showing an exemplary embodiment of an operation ofan electronic device depending on use modes for various solar cells.

First, referring to FIG. 11, three types of solar cells are used in atest. A first solar cell is the solar cell using a polycrystallinesemiconductor, and a second solar cell and a third solar cell are solarcells using an amorphous semiconductor. Since solar cells aremanufactured by different manufacturers, solar cells show differentcharacteristics.

Furthermore, referring to FIG. 11, the test is performed for each of acase in which sun light is irradiated to each solar cell (indicated by‘S’) and a case in which a halogen lamp is irradiated to each solar cell(indicated by ‘L’).

Referring to FIG. 11, in an active mode as a case of using the solarcells while sufficiently showing a performance of the electronic device,the test is performed on a bais of a case in which a backlight unit,e.g., LCD backlight unit (“BLU”), generates luminance of about 200 nits.In a low dimming mode as a case of using the solar cells by minimizingthe performance of the electronic device, the test is performed on abasis of a case in which the backlight unit generates luminance of 20nits. Lastly, in a power off mode, the test is performed while the powerof the electronic device is off.

According to each graph, the output of the solar cell is substantiallyhigher in using the sun light than in using the halogen lamp. However,when the backlight unit generates the luminance of about 200 nits(active mode), the power consumption cannot be covered by only the solarcell, and as a result, the whole inputted output of the solar cellinputted to the device is consumed in the backlight unit.

However, in the low dimming mode, only a part of the output of the solarcell is used and the remaining output of the solar cell is charged, andin the power off mode, the whole output of the solar cell is charged inthe battery.

According to FIG. 11, each solar cell has a respective characteristic.That is, since the first solar cell has an excellent current productioncapacity with respect to the halogen lamp, the first solar cell may beused in electronic devices mainly used indoors, and since the thirdsolar cell has the current production capacity with respect to the sunlight, the third solar cell may be used in electronic devices mainlyused outdoors.

As described above, the exemplary embodiments of the disclosure providesactively controlling an output of a solar cell according to anoperational state of the electronic device using the solar cell, anoutput of the solar cell is stored in a battery while the electronicdevice is not used, and the output of the solar cell is controlled to beimmediately used for the electronic device while the electronic deviceis used. Furthermore, the electronic device is used, but remaining powermay be stored in a battery when power (voltage or current) lower thanthe output of the solar cell is used. The invention may be formed byvarious exemplary embodiments, and in this application, one exemplaryembodiment embodied through drawings will be primarily described.However, the general inventive concept is not limited to the exemplaryembodiment shown in the drawings.

While this invention has been described in connection with what ispresently considered to be practical exemplary embodiments, it is to beunderstood that the invention is not limited to the disclosedembodiments, but, on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the appended claims.

What is claimed is:
 1. An electronic device using a solar cell,comprising: the solar cell; a main body which includes a display unit, abattery, and a processing unit; and a power controller which connectsthe solar cell and the main body and controls the electronic device sothat power generated from the solar cell is stored in the battery orused in the main body depending on a state of the main body.
 2. Theelectronic device of claim 1, wherein: the power controller includes: aninput terminal for the solar cell which receives an output of the solarcell; an output terminal for storage connected with an input terminal ofthe battery of the main body; an output terminal for consumptionconnected with at least one of a power terminal of the display unit anda power terminal of the processing unit of the main body; and an inputterminal for the battery connected with an output terminal of thebattery which supplies power to at least one of the power terminal ofthe display unit and the processing unit of the main body.
 3. Theelectronic device of claim 2, wherein: the power controller transmitsthe output of the solar cell inputted to the input terminal for thesolar cell to the battery through the output terminal for the storage,when at least one of the display unit and the processing unit of themain body does not operate.
 4. The electronic device of claim 2,wherein: the power controller transmits the output of the solar cellinputted to the input terminal for the solar cell to at least one of thedisplay unit and the processing unit of the main body through the outputterminal for consumption, when at least one of the display unit and theprocessing unit of the main body operates.
 5. The electronic device ofclaim 4, wherein: the power controller combines an output of the batteryinputted from the input terminal for the battery and the output of thesolar cell to output the combined output to the output terminal forconsumption.
 6. The electronic device of claim 4, wherein: the powercontroller stores a part of the output of the solar cell inputted to theinput terminal of the solar cell in the battery through the outputterminal of the storage.
 7. The electronic device of claim 2, wherein:the power controller further includes: a switching unit which isconnected between the input terminal for the solar cell and the outputterminal for the storage and operates depending on an input value of theinput terminal for the battery; and a power output unit which isconnected with each of the input terminal for the solar cell and theinput terminal for the battery to receive the output of the solar celland the output of the battery and combines the output of the solar celland the output of the battery to transmit the combined output to theoutput terminal for consumption.
 8. The electronic device of claim 7,wherein: the power output unit includes: an input diode for the solarcell connected in a forward direction from the input terminal for thesolar cell; and an input diode for the battery connected in a forwarddirection from the input terminal for the battery.
 9. The electronicdevice of claim 7, wherein: the switching unit includes a switching unittransistor, and an input terminal of the switching unit transistor isconnected to the input terminal for the solar cell, an output terminalof the switching unit transistor is connected to the output terminal forthe storage, and a control terminal is connected with the input terminalfor the battery.
 10. The electronic device of claim 9, wherein: thepower controller further includes: a diode which prevents power leak ofthe battery connected between the output terminal of the switching unittransistor and the output terminal for the storage in a forwarddirection from the output terminal of the switching unit transistor. 11.The electronic device of claim 9, wherein: the power controller furtherincludes: a switch controller formed between the input terminal for thebattery and the control terminal of the switching unit transistor, theswitch controller includes a switch controller transistor, and an inputterminal of the switch controller transistor is connected with thecontrol terminal of the switching unit transistor, an output terminal isconnected with a ground, and a control terminal is connected with theinput terminal for the battery.
 12. The electronic device of claim 11,wherein: a first resistor is formed between the output terminal of theswitch controller transistor and ground, a first node is disposedbetween the control terminal of the switch controller transistor and theinput terminal for the battery, the first node is connected with theground through a second resistor, and the second resistor has aresistance higher than that of the first resistor.
 13. The electronicdevice of claim 12, wherein: the first node is also connected with thepower output unit and an input diode for the battery formed in a forwarddirection from the first node is included in the power output unit. 14.The electronic device of claim 11, wherein: the switching unittransistor and the switch controller transistor are PNP typetransistors.
 15. The electronic device of claim 7, further comprising:an input terminal capacitor connected between the input terminal for thesolar cell and ground.
 16. The electronic device of claim 2, wherein:the processing unit includes an input device.